Diaphragm for the sound-boxes of talking-machines.



. J. SGHMITTINGER. I DIAPHRAGM FOR THE SOUND BOXES OF TALKING MACHINES. APPLICATION FILED MAY 16, 1912.

41,104,833. v Patented July 2 ,1914

ORI /N L FINISHED DIAPHRAGM a Q 1 P P a a I 4 rd Z FINISHED $KlN- TREATED rum 1 r FORMALDEHYDE AND AN :ALKALI; srmsrcmso I 0/ A/?VD DRYm/q a citizen of the United UNITED STATES PATENT curios.

J' OHN SCHMITTINGER OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR T'Cv HOSMER W. HANNA, OF PHILADELPHIA, PENNSYLVANIA.

' To all whom it may 00mm Be it known that I, JoHN SoHMIr'rINeEu, States, residing in Philadelphia, Pennsylvania, have invented Improvements in Diaphragms for the Sound-Boxes of Talking-Machines, of which the following is a specification.

My invention relatesto diaphragms for sound reproducing apparatus, more particularly the sound-boxes employed with talking machines; and the object of my invent-ion is to provide an improved form of diaphragm designed to produce a softer tone than diaphragms heretofore employed for the same purpose.

It is well known that it is impossible to obtain the best results with sound reproducing diaphragms made of the ordinary materials now in common use, such as metal, paper, mic-a, &-c., and while mica perhaps has gone into greater use than other materials, such diaphragms are extremely fragile and very expensive owing to the waste incident to the making of disks of the proper size.

My improved diaphragm is made of an animal skin or inltegument treated in a peculiar and particular manner, which treatment results in the production of a diaphragm capable, when employed as a reproducing agent in talking machine of the graphophone or phonograph type, of producing pleasing tones, avoiding the harshness and scratchiness common in the use of many articles of this kind. In the accompanying drawings, I have illustrated more-or less diagrammatically the steps in the treatment of the material of which the diaphragms forming the sub ject of my invention are made, in which:

Figure 1, is a plan view of a skin from which the diaphragm s are subsequently cut, showing the same before treatment; Fig. 2, is a view showing the treated skin mounted in a stretching frame; Fig. 3, is a view of the finally treated skin, illustrating the cutting of the diaphragms therefrom; Fig. l, shows the finished diaphragms, and Fig. 5, shows a pile ofthe finished diaphragms weighted to insure maintenance of the same in a fiat condition.

The material from which my improved diaphragms are made is that employed by banjo-makers for the banjo heads, being a.

' calf skin which has been tanned in a pccuh DIAP HRAGM rou 'rHE' sounnsoxns or reLnine-maonruns.

. Specification of Letters Patent. Application filed May 15,1912. Serial No. 697,534.

iar manner to form what is technically known as vellum. Ot such skins, I preter to use the port-ion taken from'the back otthe calf adjacent the backbone, and it is desirable that these skins be taken from calves as young as possible, preferably those new-born. v i

In some instances goat skins prepared for the same or similar purpose may be employed as the raw material. from which my improved diaphragms are made.

In the drawings, 1 represents a skin in the condition received from the tanner. The Skins thus procured are subjected to a bath consisting of about sixteen ounces of formaldehyde, (the usual 40% commercial solution of formic aldehyde), in which has been dissolved ab'out'one ounce of a suitable alkali, caustic potash (potassium hydrate), being preferred. The skins may be kept. in such bath for a period of about 5 to 10 minutes, as may be necessary to effect substan tially a retanning of the same and to soften them sulliciently to insure stretching whereby they are increased in area and reduced in thickness. After this treatment, the skins are rinsed in cold water to remove all traces of the formaldehyde and caustic potash, and then they are placed in a suitable stretching frame 2, such as shown in Fig. 2 and dried.

hen dry, the skins will be found to be much thinner, tougher, and substantially transparent, the original raw skin .having been opaque; making ideal diaphragms. They may be out from the skin as illustrated in Fig. 3 by suitable means into the desired disks, shown at 1 Fig. 4, which may be placed directly in the sound boxes, or packed away for further use. In the latter case they are preferably kept under more or less pressure as by means of a weight 5 to avoid warping or wrinkling.

In use there is no tendency of the dia phragrns to swell or loosen, remaining perfectly taut, and in practice there seems to be some slight tendency to shrink; enhancing their vibratory qualities.

I claim:

1. A diaphragm for sound recording and reproducing machines, comprising a disk of previously tanned animal fiber hardened and toughened by the action of formaldehyde.

52. A diaphragm for sound recording and the desired retell-treasur 23,4914.

4. A diaphragm for sound recording and reproducing machines, comprising a disk of" copies ot this potent my be obtained for live cents each, by addressing the action of formaldehyde and calf skin previously tanned to the form of vellum,- hardened and toughened by the causticv potash.

In testimony whereof, I have signed my 15 name to this specification, in the presence of two subscribing witnesses.

' JOHN SCHMITTINGER.

Witnesses: I

MURRAY C. BOYER, Jos. H. KLEIN.

Commissioner 0! Patents.

Washiniton, D. G." 

